Explanation: Excel uses the method of least squares to find a line that best fits the points. The R-squared value equals 0.9295, which is a good fit. The closer to 1, the better the line fits the data. The trendline predicts 120 sold wonka bars in period 13. You can verify this by using the equation. y = 7.7515 * 13 + 18.267 = 119.0365..